Rubber compositions including siliceous fillers

ABSTRACT

Vulcanizates with desirable properties can be obtained from compositions incorporating polymers that include hydroxyl group-containing aryl functionalities, silica or other particulate filler(s) that contain or include oxides of silicon and a group or compound that can act to covalently bond the filler particles and the polymer. The group can be provided as a substituent of the filler particle, or a discreet compound can be provided in the composition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional patentapplications 61/308,985, filed 28 Feb. 2010, and 61/355,461, filed 16Jun. 2010, the entire disclosures of which are incorporated by referenceherein.

BACKGROUND INFORMATION

Traction performance is one of the primary evaluation criteria for tiretreads, and performance on wet surfaces such as snow and ice is animportant factor in that evaluation.

Deformation of tread rubber induced by road surface asperities, rate ofwater drainage between the tread and road surface, and possible adhesiveinteractions at the interface between tread and road are some of thecomplex, interrelated factors that complicate the type of quantitativemechanistic understanding needed to formulate tread compounds. Tofurther improve tire performance, those involved in tread design andmanufacture continue to investigate the numerous factors that affect wettraction.

Rubber goods such as tire treads are made from elastomeric compositionsthat contain one or more reinforcing materials; see, e.g., TheVanderbilt Rubber Handbook, 13^(th) ed. (1990), pp. 603-04. The firstmaterial commonly used as a filler was carbon black, which imparts goodreinforcing properties and excellent wear resistance to rubbercompositions. However, carbon black-containing formulations often sufferfrom increased rolling resistance which correlates with an increase inhysteresis and heat build-up during operation of the tire, propertieswhich need to be minimized to increase motor vehicle fuel efficiency.

Increased hysteresis resulting from the use of carbon black can besomewhat counteracted by reducing the amount (i.e., volume) of and/orincreasing the particle size of the carbon black particles, but therisks of deterioration in reinforcing properties and wear resistancelimits the extent to which these routes can be pursued.

Over the last several decades, use of amorphous silica and treatedvariants thereof, both alone and in combination with carbon black, hasgrown significantly. Use of silica fillers can result in tires withreduced rolling resistance, increased traction on wet surfaces, andother enhanced properties.

In the search for further and/or additional enhancements, alternative ornon-conventional fillers have been investigated. Examples includevarious metal hydroxides and oxides, macroscopic (e.g., 10 -5000 μm meandiameter) particles of hard minerals such as CaCO₃ and quartz, pumicecontaining SiO₂, micron-scale metal sulfates, as well as clays andcomplex oxides.

Regardless of the type(s) of reinforcing filler(s) used in a rubbercompound, enhancing dispersion of the filler(s) throughout the polymerscan improve processability of the compound (rubber composition) andcertain physical properties of vulcanizates made therefrom. Efforts inthis regard include high temperature mixing in the presence ofselectively reactive promoters, surface oxidation of compoundingmaterials, surface grafting, and chemically modifying the polymer(s).

Chemical modification of polymers often occurs at a terminus. Terminalchemical modification can occur by reaction of a terminally active,i.e., living (i.e., anionically initiated) or pseudo-living, polymerwith a functional terminating agent. Terminal modification also can beprovided by means of a functional initiator, in isolation or incombination with functional termination. Functional initiators typicallyare organolithium compounds that additionally include otherfunctionality, typically a nitrogen atom-containing moiety. Manyfunctional initiators have relatively poor solubility in hydrocarbonsolvents of the type commonly used in anionic polymerizations and cannotmaintain propagation of living ends as well as more common alkyllithiuminitiators such as butyllithium; both characteristics unfortunatelyimpact polymerization rate and efficiency negatively.

Polymers incorporating 3,4-dihydroxyphenylalanine (DOPA) have beensynthesized for some time, often for adhesive applications; see, e.g.,U.S. Pat. No. 4,908,404. Because these polymers can be costly anddifficult to produce, so-called bulk polymers approximating theirperformance have been pursued. One such process is described in Westwoodet al., “Simplified Polymer Mimics of Cross-Linking Adhesive Proteins,”Macromolecules 2007, 40, 3960-64, although the de-protection stepemployed cannot be used when the polymer contains ethylenicunsaturation. A less restrictive approach is described in U.S. patentpubl. no. 2011/0286348, which provides a functional polymer thatexhibits excellent interaction with various types of reinforcingfillers. The interaction between the hydroxyl group(s) of thehydroxyaryl moiety and the surface of a silica particle, whilesignificant, probably does not involve formation of a covalent bond.

Providing additional, enhanced affinity between hydroxyaryl moieties andthe silica surface via formation of a covalent bond therebetween remainsdesirable.

SUMMARY

Vulcanizates with desirable properties can be obtained from compoundsemploying polymers that include a hydroxyl group-containing arylfunctionality, silica (or other types of filler(s) that contains oxidesof silicon, e.g., kaolin clay) and an entity that can act to link orbond the functionality and filler particles. In such compounds, thepolymers exhibit enhanced interactivity with reinforcing silicaparticles.

In one aspect is provided a method of making a rubber composition. Therubber composition is provided by blending a polymer with either (1)filler particles that include oxides of silicon and bound residues ofone or more compounds having the general formula

YR¹L   (I)

or (2) one or more formula I compounds and filler particles that includeoxides of silicon. In formula I, Y is a group that includes a group thatcan react with the polymer functionality (specifically an OR-substitutedaryl group or one of its oxidation products, described below); R¹ is ahydrocarbylene group (i.e., a divalent hydrocarbyl group); and L is agroup that contains at least one Si—O bond. In option (1), L iscovalently bonded to the filler particles while, in option (2), L iscapable of forming covalent bonds with the filler particles. The polymerincludes ethylenic unsaturation, typically provided from polyene mer,and pendent or terminal functionality that includes an aryl groupincluding at least one, preferably two, OR substituents, with R being Hor a hydrolyzable protecting group.

The method can include an additional step of allowing the polymer toreact with bound residues of formula I compounds (in option (1) above)or the formula I compounds (in option (2) above) so as to result in oneor more particles being covalently bonded to the polymer, i.e., throughthe radical or residue of the formula I compound. A representation ofthe structure of this polymer-particle compound is shown below ingeneral formula VIII.

In another aspect is provided a rubber composition that includes apolymer and either (1) filler particles that include oxides of siliconand bound residues of one or more formula I compounds or (2) one or moreformula I compounds and filler particles that include oxides of silicon.In the rubber composition, one or more particles can be attached to thepolymer via the radical or residue of the formula I compound. Thepolymer has ethylenic unsaturation, typically provided from polyene mer,and pendent or terminal functionality that includes an aryl groupincluding at least one, preferably two, OR substituents.

In the foregoing aspects, the polymer that includes ethylenicunsaturation and pendent or terminal functionality that includes an arylgroup including at least one, preferably two, OR substituents (referredto herein as a “functionalizing unit”) can be provided in a variety ofways. First, the functionalizing unit can be provided from initiatingcompounds that have the general formula

R³ZQ-M   (II)

where M is an alkali metal atom; R³ is a substituted or unsubstitutedaryl group having at least one OR⁴ substituent group where each R⁴ is ahydrolyzable protecting group that also is nonreactive toward M; Z is asingle bond or a substituted or unsubstituted alkylene (acyclic orcyclic) or arylene group; and Q is a group bonded to M through a C, N orSn atom. The R³ aryl group can include a single aromatic ring (phenylgroup) or two or more fused aromatic rings. Initiation with this type offunctional initiator can result in a macromolecule that includes atleast one polymer chain having terminal functionality defined by thegeneral formula

—Q′ZR⁵   (III)

or a functionalized polymer defined by the general formula

K-π-Q′ZR⁵   (IV)

where R⁵ is an aryl group that includes at least one OR substituentgroup, optionally including one or more other types of substituents; Zis defined as above; Q′ is the radical of Q, i.e., the residue of aninitiating moiety bonded to the polymer chain through a C, N or Sn atom;π is a polymer chain; and κ is a hydrogen atom or a functionalgroup-containing radical generated by reaction of the polymer with aterminating compound. Where more than one OR group is present in R⁵,each can be on the same or different rings and, in certain embodiments,at least two OR substituents can be adjacent.

Where a functionalizing unit results from a monomer, the monomer caninclude an aryl group, preferably a phenyl group, that has at least onedirectly bonded OR group. The resulting polymer can include multiple merresulting from incorporation of alkenes (A units) and at least two merof the type just described (B units) which can be non-adjacent or canconstitute a block within the polymer. If a block of B units is present,it can be relatively close to a terminus of the polymer, i.e., no morethan six, four or two polymer chain atoms from a terminal unit. In otherembodiments, one or more B units can be incorporated into the polymer,typically after polymerization of the other monomers has beenaccomplished, optionally followed by reaction with a compound whichoptionally can provide additional terminal functionality to the polymer.(This compound need not be of a type capable of providing the specificfunctionality shown below in formula V and, instead, can provide any ofa variety of functionalities including inter alia those containing oneor more heteroatoms.)

Where a functionalizing unit results from reaction of a reactive polymerwith a terminating compound, that functionality can have the generalformula

where Z′ is a single bond or an alkylene group; R⁵ is defined as above,preferably including at least two OR substituent groups; R⁶ is H, asubstituted or unsubstituted aryl group which optionally can include oneor more hydrolyzable protecting groups, R′, or JR' where J is O, S, or—NR′ (with each R′ independently being a substituted or unsubstitutedalkyl group); and Q″ is the residue of a functionality that is reactivewith at least one type of reactive polymer but which itself isnon-reactive toward such polymers.

In formulas III to V, the R⁵ aryl group can include a single aromaticring (phenyl group) or two or more fused aromatic rings, and theprotected hydrolyzable groups can be on the same or different rings ofthe aryl group although, in certain embodiments, the protectedhydrolyzable groups advantageously can be bonded to adjacent ring Catoms. In formula V, R⁶ and a portion of R⁵ can be linked so that,together with one or more atoms of the Q″ group to which they are bonded(and optionally Z′), they form a ring that is bound to or fused with theR⁵ aryl group; examples include any of a variety of flavone- andanthrone-type structures which have one or more hydrolyzable protectinggroups on at least one of the aryl groups. This is described in moredetail below in connection with formula Vb.

In certain embodiments, the polyene(s) can be conjugated dienes. Inthese and other embodiments, the polymer also can include vinyl aromaticmer which preferably are incorporated substantially randomly with theconjugated diene mer along the polymer chain.

In each of the foregoing, the polymer can be substantially linear. Incertain embodiments, the substantially linear polymer can include as aterminal moiety the radical of a compound that includes at least onearyl group having one or more substituent groups that provide hydroxylgroups upon hydrolysis.

Other aspects of the present invention will be apparent to theordinarily skilled artisan from the description of various embodimentsthat follows. In that description, the following definitions applythroughout unless the surrounding text explicitly indicates a contraryintention:

-   -   “polymer” means the polymerization product of one or more        monomers and is inclusive of homo-, co-, ter-, tetra-polymers,        etc.;    -   “mer” or “mer unit” means that portion of a polymer derived from        a single reactant molecule (e.g., ethylene mer has the general        formula —CH₂CH₂—);    -   “copolymer” means a polymer that includes mer units derived from        two reactants, typically monomers, and is inclusive of random,        block, segmented, graft, etc., copolymers;    -   “interpolymer” means a polymer that includes mer units derived        from at least two reactants, typically monomers, and is        inclusive of copolymers, terpolymers, tetra-polymers, and the        like;    -   “random interpolymer” means an interpolymer having mer units        derived from each type of constituent monomer incorporated in an        essentially non-repeating manner and being substantially free of        blocks, i.e., segments of three or more of the same mer;    -   “reactive polymer” means a polymer having at least one site        which, because of the presence of an associated catalyst or        initiator, readily reacts with other molecules, with the term        being inclusive of, inter alia, pseudo-living and carbanionic        polymers;    -   “catalyst composition” is a general term encompasses a simple        mixture of ingredients, a complex of various ingredients that is        caused by physical or chemical forces of attraction, a chemical        reaction product of some or all of the ingredients, or a        combination of the foregoing, the result of which is a        composition displaying catalytic activity with respect to one or        more monomers of the appropriate type;    -   “gum Mooney viscosity” is the Mooney viscosity of an uncured        polymer prior to addition of any filler(s);    -   “compound Mooney viscosity” is the Mooney viscosity of a        composition that includes, inter alia, an uncured or partially        cured polymer and particulate filler(s);    -   “substituted” means containing a heteroatom or functionality        (e.g., hydrocarbyl group) that does not interfere with the        intended purpose of the group in question;    -   “directly bonded” means covalently attached with no intervening        atoms or groups;    -   “polyene” means a molecule with at least two double bonds        located in the longest portion or chain thereof, and        specifically is inclusive of dienes, trienes, and the like;    -   “polydiene” means a polymer that includes mer units from one or        more dienes;    -   “phr” means parts by weight (pbw) per 100 pbw rubber;    -   “non-coordinating anion” means a sterically bulky anion that        does not form coordinate bonds with the active center of a        catalyst system due to steric hindrance;    -   “non-coordinating anion precursor” means a compound that is able        to form a non-coordinating anion under reaction conditions;    -   “radical” or “residue” means the portion of a molecule that        remains after reacting with another molecule, regardless of        whether any atoms are gained or lost as a result of the        reaction;    -   “bound residue” means a radical that is bonded to, adsorbed to,        absorbed to or otherwise strongly associated with the surface of        a particulate material;    -   “aryl group” means a phenyl group or a polycyclic aromatic        radical;    -   “terminus” means an end of a polymeric chain; and    -   “terminal moiety” means a group or functionality located at a        terminus.

Throughout this document, all values given in the form of percentagesare weight percentages unless the surrounding text explicitly indicatesa contrary intention. The relevant portions of any mentioned patent orpatent publication is incorporated herein by reference.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

As apparent from the foregoing Summary, the method can involve any of avariety of possible permutations or combinations thereof, and theresulting rubber compound or composition can be characterized in avariety of ways. Generally, a functionalized polymer of the compositionincludes mer derived from one or more polyenes, particularly dienes, andterminal functionality defined by either or both of formulas III and Vand/or one or more of the aforedescribed B mer units. In at leastcertain embodiments, the polymer also can include directly bondedpendent aromatic groups.

The following describes the production and use of a polymer thatincludes multiple A mer, i.e., alkene units; optionally, multiple C mer,i.e., units that include a pendent aryl group, particularly a phenylgroup; and, where at least some of the desired functionalization is tobe derived from functional monomers, at least one B mer, i.e., a unitthat includes a pendent aryl, preferably phenyl, group with at least onedirectly bonded OR group. Each of the A, B and C mer can result fromincorporation of ethylenically unsaturated monomers.

The A mer typically result from incorporation of polyenes, particularlytrienes (e.g., myrcene) and dienes, particularly C₄-C₁₂ dienes and evenmore particularly conjugated dienes such as 1,3-butadiene,1,3-pentadiene, 1,3-hexadiene, 2,3-dimethyl-1,3-butadiene,2-ethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene,isoprene, 4-methyl-1,3-pentadiene, 2,4-hexadiene, and the like. Some orall of the A mer can be derived from one or more types of dienes,particularly one or more types of conjugated dienes, e.g.,1,3-butadiene. In some embodiments, essentially all (i.e., at least 95%)of the polyenes can be dienes, particularly conjugated dienes.

Polyenes can incorporate into polymeric chains in more than one way.Especially for tire tread applications, controlling this manner ofincorporation can be desirable. A polymer chain with an overall1,2-microstructure, given as a numerical percentage based on totalnumber of polyene units, of from ˜10 to ˜80%, optionally from ˜25 to˜65%, can be desirable for certain end use applications. A polymer thathas an overall 1,2-microstructure of no more than ˜50%, preferably nomore than ˜45%, more preferably no more than ˜40%, even more preferablyno more than ˜35%, and most preferably no more than ˜30%, based on totalpolyene content, is considered to be substantially linear. For certainend use applications, keeping the content of 1,2-linkages even lower,e.g., to less than about 7%, less than 5%, less than 2%, or less than1%, can be desirable.

Depending on the intended end use, one or more of the polymer chains caninclude pendent aryl groups (C mer) which can be provided from vinylaromatics, particularly the C₈-C₂₀ vinyl aromatics such as, e.g.,styrene, a-methyl styrene, p-methyl styrene, the vinyl toluenes, and thevinyl naphthalenes. When used in conjunction with one or more polyenes,C mer can constitute from ˜1 to ˜50%, from ˜10 to ˜45%, or from ˜20 to˜40% of the polymer chain; random microstructure can provide particularbenefit in some end use applications such as, e.g., rubber compositionsused in the manufacture of tire treads. Where a block interpolymer isdesired, C units can constitute from ˜1 to ˜90%, generally from ˜2 to˜80%, commonly from ˜3 to ˜75%, and typically ˜5 to ˜70% of the polymerchain. (In this paragraph, all percentages are mole percentages.)

Exemplary interpolymers include those in which one or more conjugateddienes are used to provide the A units, i.e., polydienes; among these,1,3-butadiene can be one of several or the only polydiene employed.Where C units are desired, they can be provided from styrene so as toprovide, for example, SBR. In each of the foregoing types of exemplaryinterpolymers, one or more B units also can be incorporated.

B units include a pendent aryl group which includes one or more directlybonded hydroxyl groups. Because the H atoms of hydroxyl groups areactive and can interfere with certain polymerization processes, the oneor more B units typically are provided from compounds that includegroups that are non-reactive in the types of conditions utilized whenpolymerizing ethylenically unsaturated monomers but which later can beremoved, typically by hydrolysis or similar reaction, so as to providethe desired hydroxyl groups. The particular type(s) of protectinggroup(s) employed should not interfere with the polymerization process,and the de-protection process employed to provide hydroxyl groups shouldnot destroy or otherwise react with ethylenic unsaturation in thepolymer resulting from the presence of A units. A non-limiting class ofuseful protecting groups is trialkylsiloxy groups, which can be providedby reacting hydroxyl groups with a trialkylsilyl halide. While thefollowing examples employ tert-butyldimethylsiloxyl groups, others suchas acetal, tert-butyl ether, 2-methoxyethoxy ether, and the like alsocan be used.

B units typically are provided from vinyl aromatic compounds thatinclude one or more hydroxyl-producing groups directly attached to theiraryl, typically phenyl, rings. Such compounds can be represented by thegeneral formula

CH₂═CHR³   (VI)

where R³ is defined as above and which here can include from 1 to 5inclusive OR⁴ groups with each R⁴ independently being the type ofprotecting group described above. (Although each R⁴ need not beidentical, ease and simplicity typically result in a single type of R⁴moiety being used in a given compound.) The OR⁴ groups can besubstituents of the same ring of R³ or can be substituents of differentrings and, where R³ contains three or more OR⁴ groups, two of them canbe substituents of one ring with the other(s) being substituent(s) ofother ring(s). In one embodiment, two OR⁴ groups can be at the 3 and 4positions of the same ring within the aryl group, preferably a phenylgroup. Where R³ is other than a phenyl group and includes more than oneOR⁴ group and where the OR⁴ groups are on more than one ring, at leasttwo of the OR⁴ groups preferably are least somewhat proximate, i.e.,directly bonded to ring C atoms that are separated by no more than 4,preferably 3, and even more preferably 2, other ring atoms. Many ofthese compounds advantageously are soluble in the types of organicsolvents set forth below.

The number of OR groups on the aryl, typically phenyl, group of each Bunit need not be the same, where the number is the same, the OR groupsneed not be at the same position(s) on those rings. Using a phenyl groupas a representative aryl group, relative to the point of attachment ofthe phenyl group to the polymer chain, a single OR group can be locatedortho, meta, or para on the phenyl ring, while multiple OR groups can beprovided 2,3-, 2,4-, 2,5-, 2,6-, 3,4-, 3,5-, 3,6-, 2,3,4-, 2,3,5-, etc.,on the phenyl ring.

When one or more formula VI-type compounds is polymerized, it/theyprovide the B unit(s), after which each of the R⁴ moieties can behydrolyzed so as to provide phenolic hydroxyl groups.

The number of B units typically is small relative to the number of Aunits and, if present, C units; a relatively small number of B units hasbeen found to provide a satisfactory level of desired properties, withfurther improvements in those properties not necessarily beingproportional to the number of B units present. This relatively smallnumber can be expressed in a number of ways. For example, the weightpercentage of the final polymer attributable to B units commonly is lessthan 2%, more commonly from ˜0.1 to ˜1.5%, and typically from ˜0.2 to˜1.0%. The percentage of B mer relative to the total number of mer inthe polymer commonly is less than 1%, more commonly from ˜0.01 to˜0.75%, and typically from ˜0.05 to ˜0.5%. The total number of B unitsin a given polymer generally is from 1 to several dozen, commonly from 1to 12, more commonly from 1 to 10, and most commonly from 1 to 5.

The B units can be separated from one another, or two or more B unitscan be contiguous along the polymer chain. (While the ordinarily skilledartisan understands how to synthesize random and block interpolymers,each is discussed in some detail below.) Further, the B units canincorporated near the beginning of the polymerization, near the end ofthe polymerization, or at any one or more intermediate points; in thefirst two of the foregoing possibilities, a B unit can be providedwithin 6 chain atoms of, within 2 units of, adjacent to a terminus ofthe polymer, or as a terminal unit, either alone or as part of a block.

The foregoing types of polymers can be made by emulsion polymerizationor solution polymerization, with the latter affording greater controlwith respect to such properties as randomness, microstructure, etc.Solution polymerizations have been performed for many decades, so thegeneral aspects thereof are known to the ordinarily skilled artisan, soonly certain general aspects are provided here for convenience ofreference.

Both polar solvents, such as THF, and non-polar solvents can be employedin solution polymerizations, with the latter type being more common inindustrial practice. Examples of non-polar solvents include variousC₅-C₁₂ cyclic and acyclic alkanes as well as their alkylatedderivatives, certain liquid aromatic compounds, and mixtures thereof.The ordinarily skilled artisan is aware of other useful solvent optionsand combinations.

Depending on the nature of the polymer desired, the particularconditions of the solution polymerization can vary significantly. In thediscussion that follows, living polymerizations are described firstfollowed by a description of pseudo-living polymerizations. After thesedescriptions, optional functionalization and processing of polymers somade are discussed.

Solution polymerization typically involves an initiator. Exemplaryinitiators include organolithium compounds, particularly alkyllithiumcompounds. Examples of organolithium initiators includeN-lithio-hexamethyleneimine; n-butyllithium; tributyltin lithium;dialkylaminolithium compounds such as dimethylaminolithium,diethylaminolithium, dipropylaminolithium, dibutylaminolithium and thelike; dialkylaminoalkyllithium compounds such asdiethylaminopropyllithium; and those trialkyl stanyl lithium compoundsinvolving C₁-C₁₂, preferably C₁-C₄, alkyl groups.

Multifunctional initiators, i.e., initiators capable of forming polymerswith more than one living end, also can be used. Examples ofmultifunctional initiators include, but are not limited to,1,4-dilithiobutane, 1,10-dilithiodecane, 1,20-dilithioeicosane,1,4-dilithiobenzene, 1,4-dilithionaphthalene, 1,10-dilithioanthracene,1,2-dilithio-1,2-diphenylethane, 1,3,5-trilithiopentane,1,5,15-trilithioeicosane, 1,3,5-trilithiocyclohexane,1,3,5,8-tetralithiodecane, 1,5,10,20-tetralithioeicosane,1,2,4,6-tetralithiocyclohexane, and 4,4′-dilithiobiphenyl.

In addition to organolithium initiators, so-called functionalizedinitiators also can be useful. These become incorporated into thepolymer chain, thus providing a functional group at the initiated end ofthe chain. Examples of such materials include lithiated aryl thioacetals(see, e.g., U.S. Pat. No. 7,153,919) and the reaction products oforganolithium compounds and, for example, N-containing organic compoundssuch as substituted aldimines, ketimines, secondary amines, etc.,optionally pre-reacted with a compound such as diisopropenyl benzene(see, e.g., U.S. Pat. Nos. 5,153,159 and 5,567,815). Use of a Natom-containing initiator such as, for example, lithiated HMI, canfurther enhance interactivity between the polymer chains and carbonblack particles. Many of these functional initiators are poorly solublein many of the solvents set forth above, particularly those solventsthat are relatively non-polar.

In contradistinction, many compounds included in formula II exhibitacceptable solubility in the types of organic liquids commonly employedas solvents in solution polymerizations. Compounds included within thisformula hereinafter are referred to as R³-containing initiators.

The aryl group of the R³-containing initiator can be a phenyl group ortwo or more fused aromatic rings. Where the R³ aryl group includes morethan one OR⁴ group (with each R⁴ being nonreactive toward M), the OR⁴groups can be substituents of the same ring or of different rings withinthe aryl group; where the aryl group contains three or more OR⁴ groups,two of them can be substituents of one ring with the other(s) beingsubstituent(s) of other ring(s). In one embodiment, two OR⁴ groups canbe at the 3 and 4 positions of the same ring within the aryl group,preferably a phenyl group. Where R³ is other than a phenyl group andincludes more than one OR⁴ group and where the OR⁴ groups are on morethan one ring, at least two of the OR⁴ groups preferably are at leastsomewhat proximate, i.e., directly bonded to ring C atoms that areseparated by no more than 4, preferably 3, and even more preferably 2,other ring atoms. Where a single OR⁴ group is present on a phenyl group,it can be located at any ring position, with para from Z being onepreferred configuration.

The R⁴ moieties of the R³-containing initiator ensure the R³ aryl groupincludes no active hydrogen atoms, which would interfere with theability of the R³-containing initiator to anionically initiatepolymerizations. Unless a particular R⁴ moiety constitutes a groupcapable of providing interactivity with particulate filler, itpreferably also is capable of being hydrolyzed to a hydrogen atom.Trialkylsiloxy groups are a non-limiting example of the type of groupthat can serve these dual purposes; such groups can be provided byreacting hydroxyl groups attached to the R³ aryl group with atrialkylsilyl halide. Although each R⁴ need not be identical, ease andsimplicity typically result in a single type of R⁴ moiety for a givenR³-containing initiator.

When the R³-containing initiator initiates polymerization, its radicalforms one end of a polymer chain (see formulas III and IV). The R⁴moieties of this radical typically are hydrolyzed so as to providehydroxyl substituents to the R⁵ group of formulas III and IV. This typeof R⁵ group has been found to provide excellent interactivity with awide variety of particulate fillers including carbon black and silica aswell as non-conventional fillers such as inorganic oxides andhydroxides, clays and the like.

In the R³-containing initiator, M is an alkali metal atom (preferably aK, Na or Li atom, most preferably a Li atom), and Q is a group bonded toM through a C, N or Sn atom. Generally, Q does not contain any activehydrogen atoms, which would interfere with the efficacy of theR³-containing initiator. Potentially useful Q groups are too numerousfor a comprehensive listing, but a few non-limiting examples can beprovided; from these, the ordinarily skilled artisan can envisionnumerous other alternatives.

Thioacetals are one type of potentially useful Q group. Thesefunctionalities have the general formula

where R¹² is a C₂-C₁₀ alkylene group, preferably a C₂-C₈ alkylene group,more preferably a C₃-C₆ group; X is selected from S, O and NR¹³ whereinR¹³ can be a C₁-C₆ trialkylsilyl group, a C₁-C₂₀ alkyl group, a C₄-C₂₀cycloalkyl group, a C₆-C₂₀ aryl group with the proviso that any of thefollowing can be attached: C₁-C₁₀ alkyl groups, C₆-C₂₀ aryl groups,C₂-C₁₀ alkenyl groups, C₃-C₁₀ non-terminal alkynyl groups, ethers,tert-amines, phosphines, sulfides, silyls, and mixtures thereof. Onepreferred species includes an S atom as X and a C₃ alkylene group asR¹², i.e., a 1,3-dithiane. In certain aspects, Q can be a group thatincludes a hetero-atom-substituted cyclic moiety adapted to bond to analkali metal atom, such as Li. For additional information, theinterested reader is directed to U.S. Pat. No. 7,153,919.

Other potentially useful Q groups include SnR⁷ ₂ where each R⁷independently is a hydrocarbyl (e.g., alkyl, cycloalkyl, aryl, aralkyl,alkaryl, etc.) group or both together form a cycloalkyl group, and NR⁸where R⁸ is a hydrocarbyl group, particularly an aryl, a C₃-C₈cycloalkyl, or a C₁-C₂₀ alkyl group; included among the latter arecycloalkyleneiminoalkyl-lithium compounds such as those described in,for example, U.S. Pat. No. 5,574,109. Also potentially useful as Qgroups are any of a variety of linear or branched alkyl groups,non-limiting examples of which include butyl, pentyl, hexyl, heptyl,octyl, etc. All the foregoing initiators can be prepared fromhydroxyl-substituted benzaldehydes through synthesis techniquesdescribed in detail in WO 2011/002930.

Compounds defined by formula II can be provided in a variety of ways,with the choice of synthetic route depending to a large extent onparticular nature of Q. For example, a compound with multiple hydroxylgroups attached to an aryl group and at least one other functionalitycan react, through the other functionality, with a compound so as toprovide a Q group; thereafter, the H atom(s) of the hydroxyl group(s)can be reacted with a compound that can provide the aforementioned R⁴groups, and the resulting material can be reacted with an alkalimetal-containing material, e.g., an organolithium. This type ofsynthetic approach is employed in example 34 of U.S. Pat. Publ. No.2010/0286348 to provide an exemplary dithiane-type initiator.

The R³-containing initiator can be made external to the polymerizationvessel where it is to act as an initiator. In this case, a blend ofmonomer(s) and solvent can be charged to the reaction vessel, followedby addition of initiator, which often is added as part of a solution orblend (i.e., in a solvent carrier). For reasons of convenience, theR³-containing initiator typically is synthesized in situ.

Although the ordinarily skilled artisan understands the conditionstypically employed in solution polymerization, a representativedescription is provided for ease of reference. The following is based ona batch process, although the ordinarily skilled artisan can adapt thisdescription to, semi-batch, continuous, or other processes.

Solution polymerization typically begins by charging a blend ofmonomer(s) and solvent to a suitable reaction vessel, followed byaddition of a coordinator (if used) and initiator, which often are addedas part of a solution or blend; alternatively, monomer(s) andcoordinator can be added to the initiator. Both randomization and vinylcontent (i.e., 1,2-microstructure) can be increased through inclusion ofa coordinator, usually a polar compound. Up to 90 or more equivalents ofcoordinator can be used per equivalent of initiator, with the amountdepending on, for example, the amount of vinyl content desired, thelevel of non-polyene monomer employed, the reaction temperature, andnature of the specific coordinator employed. Compounds useful ascoordinators include organic compounds that include a heteroatom havinga non-bonded pair of electrons (e.g., O or N). Examples include dialkylethers of mono- and oligo-alkylene glycols; crown ethers; tertiaryamines such as tetramethylethylene diamine; THF; THF oligomers; linearand cyclic oligomeric oxolanyl alkanes (see, e.g., U.S. Pat. No.4,429,091) such as 2,2′-di(tetrahydrofuryl) propane, di-piperidylethane, hexamethylphosphoramide, N,N′-dimethylpiperazine,diazabicyclooctane, diethyl ether, tributylamine, and the like.

Typically, a solution of polymerization solvent(s) and the monomer(s) isprovided at a temperature of from about −80° to +100° C., more commonlyfrom about −40° to +50° C., and typically from ˜0° to +30° C.; to thissolution is added an initiating compound or, where a functionalizingunit is to be provided from the initiator, the R³-containing initiator(or its precursor with an organolithium, typically an alkyllithium). Thesolution can have a temperature of from about −70° to ˜150° C., morecommonly from about −20° to ˜120° C., and typically from ˜10° to ˜100°C. The polymerization is allowed to proceed under anhydrous, anaerobicconditions for a period of time sufficient to result in the formation ofthe desired polymer, usually from ˜0.01 to ˜100 hours, more commonlyfrom ˜0.08 to ˜48 hours, and typically from ˜0.15 to ˜2 hours. After adesired degree of conversion has been reached, the heat source (if used)can be removed and, if the reaction vessel is to be reserved solely forpolymerizations, the reaction mixture is removed to apost-polymerization vessel for functionalization and/or quenching.

Polymers made according to anionic techniques generally have a numberaverage molecular weight (M_(n)) of up to 500,000 Daltons. In certainembodiments, the M_(n) can be as low as ˜2000 Daltons; in these and/orother embodiments, the M_(n) advantageously can be at least ˜10,000Daltons or can range from ˜50,000 to ˜250,000 Daltons or from ˜75,000 to˜150,000 Daltons. Often, the M_(n) is such that a quenched sampleexhibits a gum Mooney viscosity (ML₄/100° C.) of from ˜2 to ˜150, morecommonly from ˜2.5 to ˜125, even more commonly from ˜5 to ˜100, and mostcommonly from ˜10 to ˜75.

Certain end use applications call for polymers that have properties thatcan be difficult or inefficient to achieve via anionic (living)polymerizations. For example, in some applications, conjugated dienepolymers having high cis-1,4-linkage contents can be desirable.Polydienes can be prepared by processes using catalysts (as opposed tothe initiators employed in living polymerizations) and may displaypseudo-living characteristics.

Certain types of catalyst systems are known to be useful in producingvery stereospecific 1,4-polydienes from conjugated diene monomers. Somecatalyst systems preferentially result in cis-1,4-polydienes, whileothers preferentially provide trans-1,4-polydienes, and the ordinarilyskilled artisan is familiar with examples of each type. The followingdescription is based on a particular cis-specific catalyst system,although this merely is for sake of example and is not considered to belimiting to the functionalizing method and compounds.

Exemplary catalyst systems can employ lanthanide metals, which are knownto be useful for polymerizing conjugated diene monomers. Specifically,catalyst systems that include a lanthanide compound can be used toprovide cis-1,4-polydienes from one or more types of conjugated dienes.Preferred lanthanide-based catalyst compositions include those describedin U.S. Pat. No. 6,699,813 and patent documents cited therein. Acondensed description is provided here for convenience and ease ofreference.

Exemplary lanthanide catalyst compositions include (a) a lanthanidecompound, an alkylating agent and a halogen-containing compound(although use of a halogen-containing compound is optional when thelanthanide compound and/or the alkylating agent contains a halogenatom); (b) a lanthanide compound and an aluminoxane; or (c) a lanthanidecompound, an alkylating agent, and a non-coordinating anion or precursorthereof.

Various lanthanide compounds or mixtures thereof can be employed, withpreference given to those which are soluble in aromatic, aliphatic,and/or cycloaliphatic liquids, although hydrocarbon-insoluble lanthanidecompounds can be suspended in the polymerization medium. Preferredlanthanide compounds include those which include at least one Nd, La, orSm atom or those including didymium. The lanthanide atom(s) in thelanthanide compounds can be in any of a number of oxidation states,although the +3 oxidation state is most common. Exemplary lanthanidecompounds include carboxylates, organophosphates, organophosphonates,organophosphinates, xanthates, carbamates, dithiocarbamates,β-diketonates, alkoxides, aryloxides, halides, pseudo-halides,oxyhalides, etc.

Typically, the lanthanide compound is used in conjunction with one ormore alkylating agents, i.e., organometallic compounds that can transferhydrocarbyl groups to another metal. These agents typically areorganometallic compounds of electropositive metals such as Groups 1, 2,and 3 metals. Exemplary alkylating agents include organoaluminumcompounds and organomagnesium compounds. The former include (1)compounds having the general formula AlR⁹ _(x)X′_(3-x) where x is aninteger of from 1 to 3 inclusive, each R⁹ independently is a monovalentorganic group (which may contain heteroatoms such as N, O, B, Si, S, P,and the like) connected to the Al atom via a C atom and each X′independently is a hydrogen atom, a halogen atom, a carboxylate group,an alkoxide group, or an aryloxide group; and (2) oligomeric linear orcyclic aluminoxanes, which can be made by reactingtrihydrocarbylaluminum compounds with water. The latter includecompounds having the general formula MgR¹⁰ _(y)X′_(2-y) where X′ isdefined as above, y is an integer of from 1 to 2 inclusive, and R¹⁰ isthe same as R⁹ except that each monovalent organic group is connected tothe Mg atom via a C atom.

Some catalyst compositions contain compounds with one or more labilehalogen atoms. Useful halogen-containing compounds include elementalhalogens, mixed halogens, hydrogen halides, organic halides, inorganichalides, metallic halides, organometallic halides, and mixtures thereof.The halogen-containing compounds preferably are soluble in solvents suchas those described above with respect to lanthanide compounds, althoughhydrocarbon-insoluble compounds can be suspended in the polymerizationmedium.

Other catalyst compositions contain a non-coordinating anion or anon-coordinating anion precursor. Exemplary non-coordinating anionsinclude tetraarylborate anions, particularly fluorinated tetraarylborateanions, and ionic compounds containing non-coordinating anions and acounteraction (e.g., triphenylcarboniumtetrakis(pentafluorophenyl)borate). Exemplary non-coordinating anionprecursors include boron compounds that include strongelectron-withdrawing groups.

Catalyst compositions of this type have very high catalytic activity forpolymerizing conjugated dienes into stereospecific polydienes over awide range of concentrations and ratios, although polymers having themost desirable properties typically are obtained from systems thatemploy a relatively narrow range of concentrations and ratios ofingredients. Further, the catalyst ingredients are believed to interactto form an active catalyst species, so the optimum concentration for anyone ingredient can depend on the concentrations of the otheringredients. The following molar ratios are considered to be relativelyexemplary for a variety of different systems based on the foregoingingredients:

-   -   alkylating agent to lanthanide compound (alkylating agent/Ln):        from ˜1:1 to ˜200:1, preferably from ˜2:1 to ˜100:1, more        preferably from ˜5:1 to ˜50:1;    -   halogen-containing compound to lanthanide compound (halogen        atom/Ln): from ˜1:2 to ˜20:1, preferably from ˜1:1 to ˜10:1,        more preferably from ˜2:1 to ˜6:1;    -   aluminoxane to lanthanide compound, specifically equivalents of        aluminum atoms on the aluminoxane to equivalents of lanthanide        atoms in the lanthanide compound (Al/Ln): from ˜10:1 to        ˜50,000:1, preferably from ˜75:1 to ˜30,000:1, more preferably        from ˜100:1 to ˜1,000:1; and    -   non-coordinating anion or precursor to lanthanide compound        (An/Ln): from ˜1:2 to ˜20:1, preferably from ˜3:4 to ˜10:1, more        preferably from ˜1:1 to ˜6:1.

The molecular weight of polydienes produced with lanthanide-basedcatalysts can be controlled by adjusting the amount of catalyst and/orthe amounts of co-catalyst concentrations within the catalyst system. Ingeneral, increasing the catalyst and co-catalyst concentrations reducesthe molecular weight of resulting polydienes, although very lowmolecular weight polydienes (e.g., liquid polydienes) require extremelyhigh catalyst concentrations which necessitates removal of catalystresidues from the polymer to avoid adverse effects such as retardationof the sulfur cure rate. Including one or more Ni-containing compoundsto lanthanide-based catalyst compositions advantageously permits easyregulation of the molecular weight of the resulting polydiene withoutsignificant negative effects on catalyst activity and polymermicrostructure. Various Ni-containing compounds or mixtures thereof canbe employed, with preference given to those which are soluble inhydrocarbon solvents such as those set forth above.

The Ni atom in the Ni-containing compounds can be in any of a number ofoxidation states, although divalent Ni compounds, where the Ni atom isin the +2 oxidation state, generally are preferred. Exemplary Nicompounds include carboxylates, organophosphates, organophosphonates,organophosphinates, xanthates, carbamates, dithiocarbamates,β-diketonates, alkoxides, aryloxides, halides, pseudo-halides,oxyhalides, organonickel compounds (i.e., compounds containing at leastone C—Ni bond such as, for example, nickelocene, decamethylnickelocene,etc.), and the like.

The molar ratio of the Ni-containing compound to the lanthanide compound(Ni/Ln) generally ranges from ˜1:1000 to ˜1:1, preferably from ˜1:200 to˜1:2, and more preferably from ˜1:100 to ˜1:5.

These types of catalyst compositions can be formed using any of thefollowing methods:

-   -   (1) In situ. The catalyst ingredients are added to a solution        containing monomer and solvent (or simply bulk monomer). The        addition can occur in a stepwise or simultaneous manner. In the        case of the latter, the alkylating agent preferably is added        first followed by, in order, the lanthanide compound, the        nickel-containing compound (if used), and (if used) the        halogen-containing compound or the non-coordinating anion or        non-coordinating anion precursor.    -   (2) Pre-mixed. The ingredients can be mixed outside the        polymerization system, generally at a temperature of from about        −20° to ˜80° C., before being introduced to the conjugated diene        monomer(s).    -   (3) Pre-formed in the presence of monomer(s). The catalyst        ingredients are mixed in the presence of a small amount of        conjugated diene monomer(s) at a temperature of from about −20°        to ˜80° C. The amount of conjugated diene monomer can range from        ˜1 to ˜500 moles, preferably from ˜5 to ˜250 moles, and more        preferably from ˜10 to ˜100 moles, per mole of the lanthanide        compound. The resulting catalyst composition is added to the        remainder of the conjugated diene monomer(s) to be polymerized.    -   (4) Two-stage procedure.        -   (a) The alkylating agent is combined with the lanthanide            compound in the absence of conjugated diene monomer, or in            the presence of a small amount of conjugated diene monomer,            at a temperature of from about −20° to ˜80° C.        -   (b) The foregoing mixture and the remaining components are            charged in either a stepwise or simultaneous manner to the            remainder of the conjugated diene monomer(s) to be            polymerized.    -    (The Ni-containing compound, if used, can be included in either        stage.)        When a solution of one or more of the catalyst ingredients is        prepared outside the polymerization system in the foregoing        methods, an organic solvent or carrier is preferably employed.        Useful organic solvents include those mentioned previously.

The production of cis-1,4-polydiene is accomplished by polymerizingconjugated diene monomer in the presence of a catalytically effectiveamount of a catalyst composition. The total catalyst concentration to beemployed in the polymerization mass depends on the interplay of variousfactors such as the purity of the ingredients, the polymerizationtemperature, the polymerization rate and conversion desired, themolecular weight desired, and many other factors; accordingly, aspecific total catalyst concentration cannot be definitively set forthexcept to say that catalytically effective amounts of the respectivecatalyst ingredients should be used. The amount of the lanthanidecompound used generally ranges from ˜0.01 to ˜2 mmol, preferably from˜0.02 to ˜1 mmol, and more preferably from ˜0.03 to ˜0.5 mmol per 100 gconjugated diene monomer. All other ingredients generally are added inamounts that are based on the amount of lanthanide compound (see thevarious ratios set forth previously).

Polymerization preferably is carried out in an organic solvent, i.e., asa solution or precipitation polymerization where the monomer is in acondensed phase. The catalyst ingredients preferably are solubilized orsuspended within the organic liquid. The amount (wt. %) of monomerpresent in the polymerization medium at the beginning of thepolymerization generally ranges from ˜3 to ˜80%, preferably ˜5 to ˜50%,and more preferably ˜10% to ˜30%. (Polymerization also can be carriedout by means of bulk polymerization conducted either in a condensedliquid phase or in a gas phase.)

Regardless of whether a batch, continuous, or semi-continuous process isemployed, the polymerization preferably is conducted with moderate tovigorous agitation under anaerobic conditions provided by an inertprotective gas. The polymerization temperature may vary widely, althoughtypically a temperature of from ˜20° to ˜90° C. is employed; heat can beremoved by external cooling and/or cooling by evaporation of the monomeror the solvent. The polymerization pressure employed may vary widely,although typically a pressure of from about 0.1 to about 1 MPa isemployed.

Where 1,3-butadiene is polymerized, the cis-1,4-polybutadiene generallyhas a M_(n), as determined by GPC using polystyrene standards, of from˜5000 to ˜200,000 Daltons, from ˜25,000 to ˜150,000 Daltons, or from˜50,000 to ˜125,000 Daltons. The polydispersity of the polymersgenerally ranges from ˜1.5 to ˜5.0, typically from ˜2.0 to ˜4.0.

Resulting polydienes advantageously can have a cis-1,4-linkage contentof at least ˜60%, at least ˜75%, at least ˜90%, and even at least ˜95%,and a 1,2-linkage content of less than ˜7%, less than ˜5%, less than˜2%, and even less than ˜1%.

Regardless of the type of polymerization process employed, at this pointthe reaction mixture commonly is referred to as a “polymer cement”because of its relatively high concentration of polymer.

Providing a terminal functionality of the type set forth above informula V can be achieved by functionalizing the polymer prior toquenching, advantageously when it is in the above-described polymercement state. One method of effecting this functionalization involvesintroducing to the polymer cement one or more aromatic compounds thatinclude a group capable of reacting with terminally active polymers aswell as one or more hydroxyl groups or hydrolyzable groups (i.e., one ormore OR substituents) and allowing such compound(s) to react at aterminus of a reactive polymer chain. This type of compound hereinafteris referred to as a terminating compound.

Where the terminating compound includes more than one OR substituent,each can be on the same ring of the aryl group, or two or more can be ondifferent rings within the aryl group. Where the aryl group containsthree or more OR substituents, all of them can be on the same ring, twoof them can be on one ring with the other(s) being on other ring(s), oreach of them can be on separate rings.

A preferred group of terminating compounds include those with an arylgroup having at least two OR substituents and, among these, preferredare those where at least two of the OR substituents are on the same ringof the aryl group. Among the latter, particularly preferred are thosewith OR substituents at the 3 and 4 positions of the same ring withinthe aryl group, preferably a phenyl group.

Examples of compounds that can be used to provide functionality such asthat shown in formula V include those defined by formulas VIIa-VIIg fromU.S. Pat. Publ. No. 2010/0286348. In the terminal functionalityrepresented by formula V, R⁶ and a portion of R⁵ can be linked so that,together with the atom(s) to which each is attached (directly orindirectly), they form a ring that is bound to or fused with the R⁵ arylgroup; this can be represented pictorially by the general formula

where each variable is described as above. These formulas are to beconsidered exemplary and not limiting. Not specifically shown in thesebut included within the scope of useful compounds are those having arylgroups other than phenyl groups, those having aryl groups not directlybonded to the carbonyl C atom, those with the carbonyl C atom bonded toan S atom rather than O (i.e., thioketo analogs), those where Z′ isother than a single bond, and the like. Where R⁵ is other than a phenylgroup, the hydroxyl substituent groups can be on the same or differentrings; when they are on more than one ring, it is preferred that they beat least somewhat proximate, i.e., that they be directly bonded to ringC atoms that are separated by no more than 4, preferably 3, and evenmore preferably 2, other ring atoms.

As suggested above, the compound itself need not include hydroxyl groupsand, instead, can include groups that are easily hydrolyzable so as toprovide hydroxyl groups after reaction. Protected compounds generallyhave structures similar to those of formulas VIIa-VIIg from U.S. Pat.Publ. No. 2010/0286348 with OR⁴ groups in place of some or all of the OHgroups; see, e.g., formula VIII from U.S. Pat. Publ. No. 2010/0286348.

Each of the compounds just discussed include a carbonyl group. Carbonylgroups provide convenient points for reaction with and attachment tocarbanionic polymer chains. Non-limiting examples of other potentiallyuseful reactive groups include aldehyde, (thio)ketone, (thio)ester,di(thio)ester, amide, epoxy, halosilane, and the like.

Reaction of these types of compound with a pre-made reactive polymer canbe performed relatively quickly (a few minutes to a few hours) atmoderate temperatures (e.g., 0° to 75° C.).

The amount of such compounds to be reacted with pre-made reactivepolymers can vary widely, depending significantly on the degree ofdesired effect, the amount of non-conventional filler(s) employed, theratio of conventional-to-non-conventional filler particles, and thelike. Based on the amount of reactive polymer chains (generallydetermined based on the equivalents of initiator or catalyst), theamount of terminating compounds capable of providing a formula V-typefunctionality can range from ˜1:10 to ˜5:4, generally from ˜1:5 to ˜9:8,and typically from ˜1:2 to ˜1:1.

Lesser amounts of terminating compounds of the type just described canbe employed in certain embodiments so as to preserve some reactivepolymer terminals for reaction with other functionalizing agents, whichcan be added before, after, or with the compounds just discussed; thistype of multiple functionalization can be avoided, at least to someextent, through use of functional initiators as discussed previously.Also, at least some embodiments of polymers having functionalitiesdefined by formulas V and Vb, as well as protected analogs, can exhibitexcellent interactivity with carbon black and silica, thereby avoidingthe need for multiple functionalization reactions.

Where the foregoing type of terminating compound is not employed but themacromolecule includes at least one functionalizing unit resulting fromeither or both of the initiator and a formula VI-type monomer,additional functionalization can result from termination with aheteroatom-containing compound including, but not limited to, Sn, Si,and N. Specific examples of alternative or additional terminatingcompounds include 1,3-dimethyl-2-imidazolidinone,3-bis(trimethylsilyl)aminopropyl-methyldiethoxysilane, as well as thosedescribed in U.S. Pat. Nos. 3,109,871, 4,647,625, 4,677,153, 5,109,907,and 6,977,281, and references cited in, and later publications citing,these patents.

At this point, the resulting polymer includes one or more types ofpolyene mer and at least one functionalizing unit which includes an arylgroup having at least one directly bonded OR substituent. Thefunctionalizing unit(s) can be derived from the initiating compound, themonomer(s), or a terminating compound. In certain aspects, more than oneof the functionalizing units can be incorporated, and these can resultfrom multiple mer, from an initiator plus one or more mer, a terminatinggroup plus one or more mer, or from all three. For reasons notcompletely understood, a polymer with formula V-type terminalfunctionality might maximize beneficial properties, both in type anddegree, in at least some types of rubber compositions.

The identity of the R moiety of the substituent (i.e., whether it is a Hatom or a protecting group) depends on the origin of the unit of whichit is a part. Units derived from an initiator and/or monomers will haveOR⁴ groups while units derived from a terminating compound can have ORgroups. Ensuring that most, preferably all, protecting groups areconverted to H atoms typically is desirable so as to promote maximuminteractivity with filler particles (when the polymer is used as part ofa rubber composition). The processing steps (including quenching)described below can be sufficient to hydrolyze at least some of theprotecting groups, thereby providing one or more hydroxyl substituentsto one or more aryl groups within polymer. Alternatively, a separatereaction step designed to promote extensive, preferably complete,hydrolysis can be employed; from the exemplary technique employed inseveral of the examples below, the ordinarily skilled artisan canenvision other potentially effective reactions. Further, the ordinarilyskilled artisan understands that OR groups, regardless of where present,may undergo further reaction during this processing and/or compoundingwith one or more types of particulate fillers (described below).

Quenching can be conducted by stirring the polymer and an activehydrogen-containing compound, such as an alcohol or acid, for up to ˜120minutes at temperatures of from ˜25° to ˜150° C.

Solvent can be removed from the quenched polymer cement by conventionaltechniques such as drum drying, extruder drying, vacuum drying or thelike, which may be combined with coagulation with water, alcohol orsteam, thermal desolvation, etc.; if coagulation is performed, ovendrying may be desirable.

Resistance to cold flow is one way in which rubbery (elastomeric)polymers sometimes are characterized. Samples can be prepared by meltpressing 2.5 g of polymer at 100° C. for 20 minutes in a mold using apreheated press; resulting cylindrical samples, which have a uniformthickness (commonly ˜12 mm) are allowed to cool to room temperaturebefore being removed from the mold. Samples are placed individuallyunder a calibrated weight (commonly 5 kg) in a Scott™ tester. Tests areconducted for a set amount of time starting from the point that theweight is released (commonly ˜30 min. for SBR samples and ˜8 min. forpolybutadiene samples), with sample thicknesses being recorded as afunction of time. Sample thickness at the conclusion of the appropriatetime generally is considered to be an acceptable indicator of cold flowresistance.

The resulting polymer can be utilized in a tread stock compound or canbe blended with any conventionally employed tread stock rubber includingnatural rubber and/or non-functionalized synthetic rubbers such as,e.g., one or more of homo- and interpolymers that include justpolyene-derived mer units (e.g., poly(butadiene), poly(isoprene), andco-polymers incorporating butadiene, isoprene, and the like), SBR, butylrubber, neoprene, EPR, EPDM, NBR, silicone rubber, fluoroelastomers,ethylene/acrylic rubber, EVA, epichlorohydrin rubbers, chlorinatedpolyethylene rubbers, chlorosulfonated polyethylene rubbers,hydrogenated nitrile rubber, tetrafluoroethylene/propylene rubber andthe like. When a functionalized polymer(s) is blended with conventionalrubber(s), the amounts can vary from about 5 to about 99% of the totalrubber, with the conventional rubber(s) making up the balance of thetotal rubber. The minimum amount depends to a significant extent on thedegree of hysteresis reduction desired.

Elastomeric compounds typically are filled to a volume fraction, whichis the total volume of filler(s) added divided by the total volume ofthe elastomeric stock, of ˜25%; accordingly, typical (combined) amountsof reinforcing fillers is ˜30 to 100 phr.

Potentially useful carbon black materials include, but not limited to,furnace blacks, channel blacks and lamp blacks. More specifically,examples of the carbon blacks include super abrasion furnace blacks,high abrasion furnace blacks, fast extrusion furnace blacks, finefurnace blacks, intermediate super abrasion furnace blacks,semi-reinforcing furnace blacks, medium processing channel blacks, hardprocessing channel blacks, conducting channel blacks, and acetyleneblacks; mixtures of two or more of these can be used. Carbon blackshaving a surface area (EMSA) of at least 20 m²/g, preferably at least˜35 m²/g, are preferred; surface area values can be determined by ASTMD-1765. The carbon blacks may be in pelletized form or an unpelletizedflocculent mass, although unpelletized carbon black can be preferred foruse in certain mixers.

The amount of carbon black utilized historically has been up to ˜50 phr,with ˜5 to ˜40 phr being typical. For certain oil-extended formulations,the amount of carbon black has been even higher, e.g., on the order of˜80 phr.

Amorphous silica (SiO₂) also commonly is used as a filler. Silicastypically are produced by a chemical reaction in water, from which theyare precipitated as ultrafine, spherical particles which stronglyassociate into aggregates and, in turn, combine less strongly intoagglomerates. Surface area gives a reliable measure of the reinforcingcharacter of different silicas, with BET (see; Brunauer et al., J. Am.Chem. Soc., vol. 60, p. 309 et seq.) surface areas of less than 450m²/g, commonly between ˜32 to ˜400 m²/g, and typically ˜100 to ˜250m²/g, generally being considered useful. Commercial suppliers of silicainclude PPG Industries, Inc. (Pittsburgh, Pa.), Grace Davison(Baltimore, Md.), Degussa Corp. (Parsippany, N.J.), Rhodia SilicaSystems (Cranbury, N.J.), and J.M. Huber Corp. (Edison, N.J.).

Aggregate particles are intended to provide the properties of two typesof fillers, particularly carbon black and silica, in a single type ofparticle; see, e.g., U.S. Pat. Nos. 6,197,274, 6,541,113, 7,199,176 andthe like. Formation of in situ synthesized siliceous fillers also isknown; see, e.g., U.S. Pat. No. 6,172,138, 6,359,034 and the like.Several clays, including kaolin, include oxides of silicon as part oftheir compositions, regardless of whether the physical form of the clayis particulate or something else. These are three examples of fillerswhich include oxides of silicon but which, in the strictest sense, arenot silica. These alternative types of silicon-containing fillers alsocan be used in rubber compositions according to the present invention.

When silica or other silicon-containing filler is employed in a rubbercompound or composition, addition of a coupling agent such as a silaneis customary so as to ensure good mixing in, and interaction with, theelastomer(s). Generally, relative to the weight of silicon-containingfiller present in the compound, the amount of added silane(s) can be ashigh as ˜20%, typically between ˜0.5 and ˜15% and, in the case ofpassenger vehicle tire treads, commonly less than 12% or even less than10%, with all of the foregoing percentages being w/w. Minimum amounts ofsilane(s) generally depend on the lowest amount of coupling effectdeemed acceptable; this amount often ranges from ˜1 to 7%, commonly from˜1.5 to ˜5% and typically from ˜2 to ˜4%. (Ranges formed by combiningthe foregoing lower and upper amounts also are envisioned.)

Silane coupling agents commonly employed in rubber compositions have thegeneral formula A′-T-G in which A′ represents a functional group capableof bonding physically and/or chemically with a group on the surface ofthe silica filler (e.g., surface silanol groups); T represents ahydrocarbon group linkage; and G represents a functional group capableof bonding or reacting with the polymeric chain of the elastomer,typically a sulfur-containing group that can react with unsaturation inthe polymer chain. Such coupling agents include organosilanes, inparticular polysulfurized alkoxysilanes (see, e.g., U.S. Pat. Nos.3,873,489, 3,978,103, 3,997,581, 4,002,594, 5,580,919, 5,583,245,5,663,396, 5,684,171, 5,684,172, 5,696,197, etc.) or polyorganosiloxanesbearing the G and A′ functionalities mentioned above. Commerciallyavailable examples of such materials includebis-(3-triethoxysilylpropyl)-tetrasulfide (Si 69™) andbis(triethoxysilylpropyl)polysulfide (Si 75™), both available fromEvonik Degussa GmbH.

The foregoing conventional silane, i.e., ones designed to link silica toa polymer via unsaturation in its chain, can be replaced in part or, attimes preferably, in whole by one or more compounds defined by formulaI. The latter generally can be understood as linking the silicaparticles (as well as other types of silicon-containing fillers) tofunctionalized polymers through the OR-substituted aryl moieties or anoxidation product thereof, particularly those at a terminus of thepolymer, as opposed to a part of the polymer chain.

In formula I, Y represents a group which is capable of covalentlybonding to a functionalizing unit or an oxidation product thereof.Examples include nitrile, isocyanate, aldehyde and ketone groups, aswell as active hydrogen atom-containing groups including but notnecessarily limited to hydroxyl, thiol, and primary or secondary amines.The amino alternatives can be represented as —NHR² where R² is H or asubstituted or unsubstituted hydrocarbyl group, typically a substitutedor unsubstituted alkyl group. Non-limiting examples of substitutedhydrocarbyl groups include —(CH₂)_(z)NR² ₂, —(CH₂)_(z)NH(CH₂)_(z)NR² ₂,—(CH₂)_(z)L (with L being defined as below), —(CH₂)_(z)NH(CH₂)_(z)L, andthe like, with z being an integer of from 1 to 12, preferably 1 to 6,and most preferably 1 to 3. Formula I compounds where Y is a thiol oramine group can be preferred in certain embodiments.

In formula I, L represents a silicon atom-containing group, morespecifically, a group that contains at least one silicon-to-oxygen(Si—O) bond. The L group often can contain two or even three Si—O bonds,i.e., a silicon atom bonded to multiple oxygen atoms. Where the siliconatom of the L group is not bonded to three oxygen atoms, the Si atomtypically will be bonded to one or two hydrocarbyl groups (includingcyclic groups, which involve the Si atom being bonded to each of theopposite ends of the hydrocarbyl group). Non limiting examples ofrepresentative L groups include

where R² is as defined above, with each R² preferably being H; R¹¹ is asubstituted or unsubstituted hydrocarbyl group such as an aryl, alkyl,alkenyl, alkenaryl, aralkenyl, alkaryl, or aralkyl group, often a C₁-C₆alkyl group; m is 1 or 2; and n is an integer of from 2 to 5 inclusive,typically 2 or 3.

The R¹ group in formula I is a hydrocarbylene that acts to link the Yand L groups. While R¹ can be an arylene, alkylene, alkenylene,alkenarylene, aralkenylene, alkarylene, or aralkylene group, an alkylenegroup with less than 12, or even less than 10, carbon atoms can bedesirable for steric reasons.

Exemplary formula I-type compounds include aminosilanes such asaminopropyltriethoxysilane, aminopropyltrimethoxysilane,4-aminobutyltriethoxysilane,3-aminopropyltris(methoxyethoxyethoxy)silane,N-(2-aminoethyl)-3-aminopropyltrimethoxysilane,N-(2-aminoethyl)-3-aminopropyltriethoxysilane,N-(6-aminohexyl)aminomethyltrimethoxysilane,N-(6-aminohexyl)aminopropyltrimethoxysilane,N-(2-aminoethyl)-11-aminoundecyltrimethoxysilane,m-aminophenyltrimethoxysilane, p-aminophenyltrimethoxysilane,(aminoethylaminomethyl)phenethyltrimethoxysilane,N-3-[(amino(polypropylenoxy)]aminopropyltrimethoxysilane,(3-trimethoxysilylpropyl)diethylenetriamine, and3-thiocyanatopropyltriethoxysilane. Preferred for at least someapplication are those formula I-type compounds that include at least oneprimary amino group, regardless of whether it is directly attached tothe R¹ group or linked through some other atoms.

As an alternative to adding a formula I-type silane as a separatecomponent, the rubber composition can employ filler particles thatinclude oxides of silicon (e.g., silica) with bound residues of one ormore formula I-type compounds. In these functionalized particles, thesilicon atom from the formula I-type compound forms one or more Si—Obonds with functional groups on the surface of the filler particle so asto link the formula I-type compound to the particle. The other end ofthe formula I-type compound residue (i.e., the Y end) remains availablefor covalently bonding with OR moieties (or oxidized variants) from thefunctionalized polymer. Non-limiting examples of commercially availablefunctionalized filler particles include Ciptane™Iγ-mercaptopropyltrimethoxysilane-treated (−3% (by wt.)) silica (PPGIndustries; Monroeville, Pa.), Nulok™ 390 aminosilane-treated kaolinclay (KaMin LLC; Macon, Ga.), Nylok™ 171 aminosilane-treated kaolin clay(KaMin LLC), Nucap™ 190W sulfur-functional, silane-treated kaolin clay(KaMin LLC).

Regardless of whether a formula I-type compound is added as a separatecomponent or provided as a bound residue of the particulate material,the resulting polymer-particle compound can be represented by thegeneral formula

π*-I*-ρ  (VIII)

where π* represents a functionalizing unit-containing polymer, ρrepresents a filler particle that includes one or more oxides ofsilicon, and I* represents a radical of a formula I compound bonded toeach of π* and ρ.

Addition of a processing aid can be used to reduce the amount of silaneemployed; see, e.g., U.S. Pat. No. 6,525,118 for a description of fattyacid esters of sugars used as processing aids. Additional fillers usefulas processing aids include mineral fillers, such as clay (hydrousaluminum silicate), talc (hydrous magnesium silicate), and mica as wellas non-mineral fillers such as urea and sodium sulfate. Preferred micascontain principally alumina, silica and potash, although other variantsalso can be useful. Processing aids can be utilized in an amount of upto ˜40 phr, typically up to ˜20 phr.

Silica, alone or as a portion of a blend of silicon-containing fillers,commonly is employed in amounts of up to ˜150 phr, commonly from ˜5 to˜90 phr, typically from ˜7 to ˜85. The useful upper range is limited bythe high viscosity that such fillers can impart. When carbon black alsois used, the amount of silica can be decreased to as low as ˜1 phr; asthe amount of silica decreases, lesser amounts of the processing aids,plus silane if any, can be employed.

One or more non-conventional fillers having relatively high interfacialfree energies, i.e., surface free energy in water values (γ_(p1)) can beused in conjunction with or in place of at least a portion of the carbonblack and/or silica. The term “relatively high” can be defined orcharacterized in a variety of ways such as, e.g., greater than that ofthe water-air interface, preferably several multiples (e.g., at least2×, at least 3× or even at least 4×) of this value; at least severalmultiples (e.g., at least 2×, at least 3×, at least 4×, at least 5×, atleast 6×, at least 7×, at least 8×, at least 9× or even at least 10×) ofthe γ_(p1) value for amorphous silica; in absolute terms such as, e.g.,at least ˜300, at least ˜400, at least ˜500, at least ˜600, at least˜700, at least ˜750, at least ˜1000, at least ˜1500, and at least ˜2000mJ/m²; in ranges such as, e.g., from ˜300 to ˜5000 mJ/m², from ˜350 to˜4000 mJ/m², from ˜400 to ˜5000 mJ/m², from ˜450 to ˜4000 mJ/m², from˜500 to ˜5000 mJ/m², and various sub-ranges within the foregoing and/orother combinations of high and low values; and the like.

Non-limiting examples of naturally occurring materials with relativelyhigh interfacial free energies include F-apatite, goethite, hematite,zincite, tenorite, gibbsite, quartz, kaolinite, all forms of pyrite, andthe like. Certain synthetic complex oxides also can exhibit this type ofhigh interfacial free energy.

The foregoing types of materials typically are more dense than eithercarbon black or amorphous silica; thus, replacing a particular mass ofcarbon black or silica with an equal mass of a non-conventional fillertypically will result in a much smaller volume of overall filler beingpresent in a given compound. Accordingly, replacement typically is madeon an equal volume, as opposed to equal weight, basis.

Generally, ˜5 to ˜60% of the conventional particulate filler material(s)can be replaced with an approximately equivalent (˜0.8× to ˜1.2×) volumeof non-conventional filler particles. In certain embodiments, replacing˜10 to ˜58% of the conventional particulate filler material(s) with anapproximately equivalent (˜0.85× to ˜1.15×) volume of other fillerparticles is sufficient; in other embodiments, replacing ˜15 to ˜55% ofthe conventional particulate filler material(s) with an approximatelyequivalent (˜0.9× to ˜1.1×) volume of other filler particles isadequate; in still other embodiments, replacing ˜18 to ˜53% of theconventional particulate filler material(s) with an approximatelyequivalent (˜0.95× to ˜1.05×) volume of other filler particles can bepreferable.

The weight inequality issue might be able to be overcome or amelioratedby employing non-standard particles. For example, one can envisionessentially hollow particles of one or more types of non-conventionalfillers as well as relatively light particles coated so as to have asurface that includes one or more of types of non-conventional fillercompounds.

The non-conventional filler particles generally can be of approximatelythe same size as the conventional fillers employed in compounds. Ingeneral, relatively small particles are preferred both for reinforcementpurposes and to ensure a large number of particles are available at thetread surface.

Other conventional rubber additives also can be added. These include,for example, process oils, plasticizers, anti-degradants such asantioxidants and antiozonants, curing agents and the like.

All ingredients can be mixed with standard equipment such as, e.g.,Banbury or Brabender mixers. Typically, mixing occurs in two or morestages. During the first stage (also known as the masterbatch stage),mixing typically is begun at temperatures of ˜120° to ˜130° C. andincreases until a so-called drop temperature, typically ˜165° C., isreached.

Where a formulation includes fillers other than carbon black, a separatere-mill stage often is employed for separate addition of the silanecomponent(s). This stage often is performed at temperatures similar to,although often slightly lower than, those employed in the masterbatchstage, i.e., ramping from ˜90° C. to a drop temperature of ˜150° C. Useof a re-mill stage, while common, is not required, and the formulaI-type compound(s) can be introduced during either the masterbatch stageor re-mill stage. Some types of silanes permit mixing at temperatures ashigh as 170°-180° C., which may allow one or more of the foregoingstages to be omitted.

Reinforced rubber compounds conventionally are cured with about 0.2 toabout 5 phr of one or more known vulcanizing agents such as, forexample, sulfur or peroxide-based curing systems. For a generaldisclosure of suitable vulcanizing agents, the interested reader isdirected to an overview such as that provided in Kirk-Othmer,Encyclopedia of Chem. Tech., 3d ed., (Wiley Interscience, New York,1982), vol. 20, pp. 365-468. Vulcanizing agents, accelerators, etc., areadded at a final mixing stage. To avoid undesirable scorching and/orpremature onset of vulcanization, this mixing step often is done atlower temperatures, e.g., starting at ˜60° to ˜65° C. and not goinghigher than ˜105° to ˜110° C.

Subsequently, the compounded mixture is processed (e.g., milled) intosheets prior to being formed into any of a variety of components andthen vulcanized, which typically occurs at ˜5° to ˜15° C. higher thanthe highest temperatures employed during the mixing stages, mostcommonly ˜170° C. Depending on particular components and conditions,vulcanization typically is performed at a temperature of from ˜140° to˜170° C.

Certain tests have come to be recognized as correlating certain physicalproperties of vulcanizates with performance of products, particularlytire treads, made therefrom. For example, reductions in hysteresis (heatbuild up during operation) have been found to correlate with higherrebound values and lower loss tangent values (tan δ) at hightemperature, better handling performance often correlates with higherelastic modulus values at high temperature and strain, ice traction hasbeen found to correlate with lower modulus values at low temperatures,etc. (In the foregoing, “high temperature” typically is considered to be˜50°-65° C. while “low temperature” is considered to be ˜0° to −25° C.)

Many desirable properties of vulcanizates (as well as enhancedprocessability of the rubber compositions from which they are prepared)are achieved when filler particles are well dispersed and exhibitexcellent interactivity with the constituent polymers. The section ofthe polymer chain from the site of the last crosslink to an end of thepolymer chain is a major source of hysteretic losses; this free end isnot tied to the macromolecular network and thus cannot be involved in anefficient elastic recovery process and, as a result, energy transmittedto this section of the polymer (and vulcanizate in which such polymer isincorporated) is lost as heat. Ensuring that these polymer chain endsare tied to, or otherwise interact well with, reinforcing particulatefillers, is important to many vulcanizate physical properties such as,for example, reduced hysteresis. Formula I-type compounds (or radicalsthereof, in the case where a functionalized silica is employed) havebeen found to assist in ensuring that the types of functional polymersdiscussed above interact well with silica and other silicon-containingfillers.

The following non-limiting, illustrative examples provide detailedconditions and materials that can be useful in the practice of theinvention just described.

EXAMPLES Examples 1-2

Two random styrene/butadiene copolymers were prepared similarly to theconditions employed in the polymer synthesis examples from U.S. patentpubl. no. 2011/0286348. Each of the resulting copolymers had a boundstyrene content of ˜20% and vinyl content (based on total butadiene mer)of ˜55%.

Polymer 1 was terminated with isopropanol while polymer 2 was reactedwith 3,4-dihydroxybenzaldehyde so as to provide a formula III-typeterminal functionality. Both copolymers were processed similarly to thepolymer from the examples in U.S. patent publ. no. 2011/0286348.

The characteristics of polymer samples 1 and 2 are displayed below inTable 1. Molecular weight data were obtained via gel permeationchromatography using polystyrene standards. Glass transition temperature(T_(g)) data were obtained via differential scanning calorimetry.

TABLE 1 Polymer characteristics 1 2 M_(w) (kg/mol) 117.5 134.5 M_(p)(kg/mol) 117.4 116.7 M_(w)/M_(n) 1.034 1.161 % coupled 0 10.9 T_(g) (°C.) −32.9 −34.5

Examples 3-12

Five filled compositions were prepared from each of polymer samples 1-2using 55 phr Hi-Sil™ 190G silica (PPG Industries). The basic compositionformula is shown below in Table 2a whereN-phenyl-N′-(1,3-dimethylbutyl)-p-phenylenediamine (6PPD) acts as anantioxidant, and 2,2′-dithiobis(benzothiazole) (MBTS),N-tert-butylbenzothiazole-2-sulfenamide (TBBS) andN,N′-diphenylguanidine (DPG) act as accelerators. Black oil is anextender oil that contains a relatively low amount of polycyclicaromatic compounds.

Si 75™ silane was used as coupling agent, with some of this conventionalsilane being replaced by aminopropyltriethoxysilane (APTEOS) in certainof the examples. The amounts of these components used in each exampleare shown in Table 2b.

Three stages of mixing (masterbatch, re-mill and final batch) werecarried out for each composition using a 65-gram Brabender™ internalmixer.

TABLE 2a Filled composition formula Amount (phr) Masterbatch synthesizedpolymer 80 poly(isoprene) (natural rubber) 20 silica 52.5 wax blend 26PPD 0.95 stearic acid 2 black oil 10 APTEOS varied Re-mill silica 2.5silane varied APTEOS varied Final sulfur 1.5 ZnO 2.5 MBTS 2.0 TBBS 0.7DPG 1.4

TABLE 2b Amounts of silanes employed in rubber compositions MasterbatchRe-mill Polymer APTEOS (phr) silane (phr) APTEOS (phr) 3 1 0 5 0 4 1 1 40 5 1 2 3 0 6 1 0 4 1 7 1 0 3 2 8 2 0 5 0 9 2 1 4 0 10 2 2 3 0 11 2 0 41 12 2 0 3 2

Examples 13-22

The filled compositions from Examples 3-12 were vulcanized at hightemperature (˜171° C.) and high pressure. Each of resulting vulcanizates13-22 was subjected to a variety of tests, the results of which aresummarized below in Table 3.

TABLE 3 Physical properties, compounds and vulcanizates 13 14 15 16 1718 19 20 21 22 Filled composition 3 4 5 6 7 8 9 10 11 12 (example no.)ML₁₊₄ @ 130° C. (final) 16.4 29.3 43.9 35.0 48.7 29.0 42.7 59.9 47.265.2 Bound rubber (%) 22.9 28.8 39.1 29.3 36.8 36.0 53.8 64.1 50.7 55.3Cure test (171° C., 30 min.) ML (dN · m) 1.71 1.79 2.30 1.96 2.25 1.431.42 1.69 1.61 1.56 MH (dN · m) 24.34 22.28 22.20 22.02 20.15 21.9917.37 15.66 17.47 17.31 t₁₀ (min) 1.64 1.19 0.72 1.06 0.64 1.34 0.920.62 0.78 0.56 t₅₀ (min) 2.59 1.76 1.07 1.64 1.01 2.09 1.35 0.93 1.180.80 t₉₀ (min) 7.84 4.44 4.42 5.40 4.49 6.23 2.91 2.47 2.81 2.12 Tensile@ 23° C. (final, unaged) M₅₀ (MPa) 2.16 1.89 1.90 2.04 1.84 1.83 1.521.35 1.50 1.61 M₁₀₀ (MPa) 3.93 3.40 3.47 3.74 3.24 3.57 2.98 2.56 2.873.17 M₂₀₀ (MPa) 8.04 7.17 7.36 7.71 6.73 8.15 7.33 6.41 6.77 7.65 M₃₀₀(MPa) 12.88 11.66 11.84 12.19 10.91 13.80 13.03 11.70 11.85 13.33 T_(b)(MPa) 13.3 14.0 12.6 12.6 11.0 15.2 15.8 14.5 16.7 13.0 E_(b) (%) 312348 317 308 305 324 347 349 390 295 Strain sweep (50° C., 15 Hz, final)G′ @ 9.92% strain (MPa) 3.11 2.95 3.10 3.04 2.88 2.51 2.15 2.07 2.192.26 tan δ @ 9.92% strain 0.194 0.196 0.194 0.188 0.196 0.123 0.1000.102 0.112 0.104 Temp. sweep (10 Hz, final) T @ peak tan δ (° C.) −20.0−19.9 −20.0 −19.9 −20.0 −20.0 −22.0 −21.9 −22.0 −22.0 peak tan δ (0.5%strain) 0.7682 0.7743 0.7692 0.7761 0.7887 0.8287 1.0124 1.0557 1.00161.0073 tan δ @ −7.0° C. 0.517 0.494 0.483 0.494 0.490 0.536 0.555 0.5700.559 0.581 (3.0% strain) Dynastat (60° C., 10 Hz, final) tan δ 0.11750.1398 0.1425 0.1286 0.1442 0.0820 0.0686 0.0732 0.0763 0.0751

The high temperature loss tangent (tan δ) measurements (Dynastat data)for examples 14-17 are higher than that of example 13, while the valuesfor examples 19-22 are lower than that of example 18. This indicatesthat the presence of APTEOS decreases hysteresis (i.e., tan δ) invulcanizates made from a composition employing an appropriate type offunctional SBR copolymer but not in vulcanizates made from a compositionemploying a similar non-functionalized SBR copolymer. Decreasedhysteresis at higher temperatures generally is considered to correlateto increased (better) polymer-filler interactivity.

Dynamic strain sweep testing conducted at 50° C. indicates that losstangent values at 9.92% strain for rubber compositions employingnon-functionalized SBR copolymers are essentially the same. However,compounds made from a composition employing an appropriatefunctionalized copolymer (examples 19-22) have significantly lower losstangent values than a similar non-functionalized copolymer (example 18).Lower loss tangents at higher temperatures (50°-60° C.) often areconsidered indicative of vulcanizates that can provide tire treads withlower rolling resistance.

Temperature sweep testing, particularly loss tangent at −7° C., showsdata values for functionalized copolymers (examples 19-22) that arehigher than that for a similar non-functionalized comparative copolymer(example 18), although no such increase is seen for examples 14-17relative to example 13. Increased loss tangent at lower temperatures(−10° to 0° C.) often are considered indicative of vulcanizates that canprovide tire treads with good skid resistance as well as, perhaps, snowand ice traction.

In a plot of tan δ vs. temperature (from a temperature sweep test) data,little change in peak height was seen for examples 13-17, but the peakheight for examples 19-22 increased relative to that of example 18.

Examples 23-24

Two more random styrene/butadiene copolymers were prepared similar tothose from Examples 1-2. Polymer 23 was terminated with isopropanolwhile polymer 24 was reacted with 3,4-dihydroxybenzaldehyde so as toprovide a formula III-type terminal functionality.

Both copolymers were processed and tested similarly to the polymers fromExamples 1-2. The characteristics of polymer samples 23 and 24 aredisplayed below in Table 4.

TABLE 4 Polymer characteristics 23 24 M_(w) (kg/mol) 128.9 147.6 M_(p)(kg/mol) 127.2 127.1 M_(w)/M_(n) 1.057 1.146 % coupled 1.8 11.2 T_(g) (°C.) −34.2 −34.6

Examples 25-32

Four filled compositions were prepared from each of polymer samples23-24 using a basic composition formula similar to the one used inconnection with examples 3-12. This formula is shown below in Table 5a.Some of the conventional (Si 75) silane was replaced by3-mercaptopropyltriethoxysilane (3-MPTEOS) in certain of the examples,with the amounts used in each exemplary compound shown in Table 5b.

TABLE 5a Filled composition formula Amount (phr) Masterbatch synthesizedpolymer 80 poly(isoprene) (natural rubber) 20 silica 52.5 wax blend 26PPD 0.95 stearic acid 2 black oil 10 3-MPTEOS varied Re-mill silica 2.5silane varied 3-MPTEOS varied Final sulfur 1.5 ZnO 2.5 MBTS 2.0 TBBS 0.7DPG 1.4

TABLE 5b Amounts of silanes employed in rubber compositions MasterbatchRe-mill polymer 3-MPTEOS (phr) silane (phr) 3-MPTEOS (phr) 25 23 0 5 026 23 0.25 5 0 27 23 0.50 5 0 28 23 0 5 0.50 29 24 0 5 0 30 24 0.25 5 031 24 0.50 5 0 32 24 0 5 0.50

Examples 33-40

The filled compositions from Examples 25-32 were vulcanized similarly tothose in Examples 13-22. Each of resulting vulcanizates 33-40 wassubjected to a variety of tests, the results of which are summarizedbelow in Table 6.

TABLE 6 Physical properties, compounds and vulcanizates 33 34 35 36 3738 39 40 Filled composition (example no.) 25 26 27 28 29 30 31 32 ML₁₊₄@ 130° C. (final) 17.9 18.6 18.7 16.5 32.5 35.1 38.8 33.5 Bound rubber(%) 17.9 30.0 35.1 23.9 41.4 51.0 60.6 49.4 Cure test (171° C., 30 min.)ML (dN · m) 1.87 1.62 1.41 1.53 1.50 1.36 1.37 1.27 MH (dN · m) 25.6024.51 23.76 24.60 21.99 20.47 19.25 21.55 t₁₀ (min) 1.83 1.84 1.67 1.631.40 1.35 1.23 1.16 t₅₀ (min) 2.94 2.87 2.66 2.68 2.35 2.16 2.07 2.00t₉₀ (min) 9.14 8.86 8.68 9.33 6.91 6.82 7.83 7.65 Tensile @ 23° C.(final, unaged) M₅₀ (MPa) 2.71 2.67 2.67 2.68 2.33 2.31 2.26 2.56 M₁₀₀(MPa) 5.21 5.16 5.28 5.23 4.81 4.97 4.98 5.48 M₂₀₀ (MPa) 11.43 11.4211.92 11.69 11.67 12.55 12.98 13.32 T_(b) (MPa) 14.4 15.2 15.0 15.1 17.016.6 14.9 15.3 E_(b) (%) 244 256 243 248 273 250 223 225 Strain sweep(50° C., 15 Hz, final) G′ @ 9.80% strain (MPa) 3.05 2.76 2.59 2.64 2.272.16 2.26 2.02 tan δ @ 9.80% strain 0.184 0.180 0.175 0.181 0.119 0.1040.101 0.101 Temp. sweep (0.5% strain, 10 Hz, final) T @ peak tan δ (°C.) −19.9 −20.0 −19.9 −19.9 −18.0 −18.0 −17.8 −17.9 peak tan δ 0.7870.794 0.795 0.794 0.887 1.022 1.048 0.960 tan δ @ −6.0° C. 0.368 0.3750.388 0.374 0.468 0.574 0.587 0.534 Dynastat (60° C., final) tan δ0.1262 0.1254 0.1258 0.1234 0.0827 0.0736 0.0703 0.0738

The data from Table 6 indicate, inter alia, that rubber compositionsemploying 3-MPTEOS with functionalized SBR copolymers (examples 38-40)exhibit significantly higher peak tan δ values (temperature sweep) andsignificantly reduced tan δ (both strain sweep testing at 50° C. as wellas Dynastat) than do similar compounds employing non-functionalizedcontrol SBR copolymers.

Examples 41-42

Two more random styrene/butadiene copolymers were prepared similar tothose from Examples 1-2. Polymer 41 was terminated with isopropanolwhile polymer 42 was reacted with 3,4-dihydroxybenzaldehyde so as toprovide a formula III-type terminal functionality.

Both copolymers were processed and tested similarly to the polymers fromExamples 1-2. The characteristics of polymer samples 41 and 42 aredisplayed below in Table 7.

TABLE 7 Polymer characteristics 41 42 M_(w) (kg/mol) 93.9 123.4 M_(p)(kg/mol) 94.7 99.2 M_(w)/M_(n) 1.034 1.176 % coupled 1.1 19.5 T_(g) (°C.) −36.6 −36.5

Examples 43-48

Three filled compositions were prepared from each of polymer samples41-42 using a composition formula similar to those used previously; theparticular formula is shown below in Table 8a. Some of the conventional(Si 75) silane was replaced by 3-MPTEOS or APTEOS in certain of thecompositions, with the amounts used in each exemplary compound shown inTable 8b.

TABLE 8a Filled composition formula Amount (phr) Masterbatch synthesizedpolymer 80 poly(isoprene) (natural rubber) 20 silica 55 wax blend 2 6PPD1 stearic acid 2 black oil 10 silane varied APTEOS varied 3-MPTEOSvaried Re-mill Final sulfur 1.5 ZnO 2.5 MBTS 2.0 TBBS 0.7 DPG 1.4

TABLE 8b Amounts of silanes employed in rubber compositions Masterbatchpolymer silane (phr) APTEOS (phr) 3-MPTEOS (phr) 43 41 5 0 0 44 41 4 1 045 41 5 0 0.5 46 42 5 0 0 47 42 4 1 0 48 42 5 0 0.5

Examples 49-54

The filled compositions from Examples 43-48 were vulcanized similarly tothose in previous examples. Each of resulting vulcanizates 49-54 wassubjected to strain sweep testing, the results of which are summarizedbelow in Table 9.

TABLE 9 Strain data, vulcanizates 49 50 51 52 53 54 Filled composition43 44 45 46 47 48 (example no.) Strain sweep (50° C., 15 Hz, final) tanδ @ 9.92% 0.214 0.210 0.208 0.166 0.142 0.148 strain % reduction from —1.9 2.8 — 14.5 10.8 comparative

The data from Table 9 indicate that vulcanizates employing a formulaI-type compound with a functionalized SBR copolymer (examples 53-54)exhibit significant reductions in hysteresis (lower tan δ values), whilevulcanizates employing those same compounds with a non-functionalizedcontrol SBR copolymer (examples 50-51) exhibit only minimal reductions,probably resulting from modifications in filler-filler interactions(aminosilane) or bonding between silica surface and backbone doublebonds (mercaptosilane).

Examples 55-58

Two more filled compositions were prepared from each of polymer samples41-42; examples 55-56 were prepared from polymer sample 41, whileExamples 57-58 were prepared from polymer sample 42. The filledcompositions were prepared using the formula shown below in Table 10,with Hi-Sil™ 210 silica (PPG Industries) being used in Examples 55 and57 and Ciptane™ I modified silica in Examples 56 and 58.

TABLE 10 Filled composition formula Amount (phr) Masterbatch synthesizedpolymer 100 silica 50 6PPD 1 stearic acid 2 black oil 10 Re-mill Finalsulfur 3 ZnO 3 MBTS 1 TBBS 1 DPG 0.5

Examples 59-62

The filled compositions from Examples 55-58 were vulcanized similarly tothose in previous examples. Each of resulting vulcanizates 59-62 wassubjected to strain sweep testing, the results of which are summarizedbelow in Table 11.

TABLE 11 Strain data, vulcanizates 59 60 61 62 Filled composition(example no.) 55 56 57 58 Strain sweep (50° C., 15 Hz, final) tan δ @9.99% strain 0.181 0.165 0.124 0.096 % reduction from comparative — 8.7— 22.4

The data from Table 11 indicate that vulcanizates employing a silicacontaining a bound residue of a formula I-type compound (examples 60 and62) exhibit significant reductions in hysteresis (lower tan δ values)than vulcanizates employing an unmodified silica (examples 59 and 61).This reduction is ˜250% greater where the modified silica is used with afunctionalized SBR copolymer (example 62) than with a non-functionalizedcontrol SBR copolymer (example 60).

Examples 63-65

Two more random styrene/butadiene copolymers were prepared similar tothose from Examples 1-2; polymer 63 was terminated with isopropanolwhile polymer 64 was reacted with 3,5-dihydroxybenzaldehyde so as toprovide a formula III-type terminal functionality.

A third styrene/butadiene interpolymer was prepared using a proceduresimilar to that from Examples 53-55 of U.S. Patent Publ. No.2011/0286348. The amount of 3,4-di(tert-butyldimethylsiloxy)styreneadded was targeted so as to provide, on average, two3,4-dihydroxystyrene mer units per interpolymer chain.

These copolymers were processed and tested similarly to the polymersfrom Examples 1-2. The characteristics of polymer samples 63-65 aredisplayed below in Table 12.

TABLE 12 Polymer characteristics 63 64 65 M_(w) (kg/mol) 132.2 146.8128.8 M_(p) (kg/mol) 132.9 133.8 121.7 M_(w)/M_(n) 1.028 1.091 1.067 %coupled 0 9.2 5.4 T_(g) (° C.) −35.4 −38.1 −35.6

Examples 66-73

Filled compositions were prepared from each of polymer samples 63-65using a composition formula similar to those used previously; thisformula is shown below in Table 13a. Some of the conventional (Si 75)silane was replaced by 3-MPTEOS or APTEOS in certain of thecompositions, with the amounts used in each exemplary compound shown inTable 13b.

TABLE 13a Filled composition formula Amount (phr) Masterbatchsynthesized polymer 80 poly(isoprene) (natural rubber) 20 silica 52.5wax blend 2 6PPD 1 stearic acid 2 black oil 10 APTEOS varied 3-MPTEOSvaried Re-mill silica 2.5 silane varied Final sulfur 1.5 ZnO 2.5 MBTS2.0 TBBS 0.7 DPG 1.4

TABLE 13b Amounts of silanes employed in rubber compositions MasterbatchRe-mill polymer APTEOS (phr) 3-MPTEOS (phr) silane (phr) 66 63 0 0 5 6763 0 0.5 5 68 64 0 0 5 69 64 1 0 4 70 64 0 0.5 5 71 65 0 0 5 72 65 1 0 473 65 0 0.5 5

Examples 74-81

The filled compositions from Examples 66-73 were vulcanized similarly tothose in previous examples. Each of resulting vulcanizates 74-81 wassubjected to strain sweep testing, the results of which are summarizedbelow in Table 14.

TABLE 14 Strain data, vulcanizates 74 75 76 77 78 79 80 81 Filledcomposition 66 67 68 69 70 71 72 73 (example no.) Strain sweep (50° C.,15 Hz, final) tan δ @ 9.92% strain 0.186 0.174 0.117 0.100 0.086 0.1710.131 0.128 % reduction from comparative — 6.5 — 14.7 26.4 — 23.4 25.2

The data of Table 14 indicate that vulcanizates employing a formulaI-type compound with a functionalized SBR copolymer (examples 80-81) orfunctionalized SBR interpolymer (examples 77-78) exhibit significantreductions in hysteresis (lower tan δ values), while a vulcanizateemploying such a compound with a non-functionalized control SBRcopolymer (examples 75) exhibits a much smaller reduction.

Examples 82-84

Three more random styrene/butadiene copolymers were prepared similar tothose from Examples 1-2; polymer 82 was terminated with isopropanolwhile polymers 83-84 was reacted with, respectively, adihydroxybenzonitrile (similar to the procedure described in examples42-46 of WO 2011/002930) and 3,4,5-trihydroxybenzaldehyde so as toprovide formula III-type terminal functionalities.

These copolymers were processed and tested similarly to the polymersfrom Examples 1-2. The characteristics of polymer samples 82-84 aredisplayed below in Table 15.

TABLE 15 Polymer characteristics 82 83 84 M_(w) (kg/mol) 122.1 169.4214.7 M_(p) (kg/mol) 121.9 121.3 110.6 M_(w)/M_(n) 1.049 1.276 1.417 %coupled 1.6 29.1 56.8 T_(g) (° C.) −40.1 −38.8 −34.9

Examples 85-92

Filled compositions were prepared from each of polymer samples 82-84using the composition formula shown above in Table 13a. The amounts ofconventional (Si 75) silane, 3-MPTEOS, and APTEOS used in thecompositions are shown in Table 16 below.

TABLE 16 Amounts of silanes employed in rubber compositions MasterbatchRe-mill polymer APTEOS (phr) 3-MPTEOS (phr) silane (phr) 85 82 0 0 5 8682 1 0 4 87 82 0 1 4 88 83 0 0 5 89 83 1 0 4 90 83 0 1 4 91 84 0 0 5 9284 0 1 4

Examples 93-100

The filled compositions from Examples 85-92 were vulcanized similarly tothose in previous examples. Each of resulting vulcanizates 93-100 wassubjected to strain sweep testing, the results of which are summarizedbelow in Table 17.

TABLE 17 Strain data vulcanizates 93 94 95 96 97 98 99 100 Filledcomposition 85 86 87 88 89 90 91 92 (example no.) Strain sweep (50° C.,15 Hz, final) tan δ @ 9.80% strain 0.196 0.191 0.169 0.139 0.115 0.1030.148 0.109 % reduction from comparative — 2.6 13.8 — 17.3 25.9 — 26.4

The data of Table 17 indicate that vulcanizates employing a formulaI-type compound with a functionalized SBR copolymer (examples 97-98 and100) exhibit significant reductions in hysteresis (lower tan δ values),while vulcanizates employing such a compound with a non-functionalizedcontrol SBR copolymer (examples 94-95) exhibit a similar but far lesserreduction.

1. A rubber composition comprising (a) a polymer comprising ethylenicunsaturation and pendent or terminal functionality that comprises anaryl group comprising at least two OR substituents, wherein R is H or ahydrolyzable group, and (b) either (1) filler particles that compriseoxides of silicon and bound residues of one or more compounds having thegeneral formula YR¹L, or (2) one or more compounds defined by thegeneral formula YR¹L and filler particles that comprise oxides ofsilicon,  where Y is a group capable of reacting with said polymerfunctionality or an oxidation product thereof, R¹ is a hydrocarbylenegroup, and L is a group that contains at least one Si—O bond.
 2. Therubber composition of claim 1 wherein said polymer comprises terminalfunctionality that comprises an aryl group comprising at least two ORsubstituents.
 3. The rubber composition of claim 2 wherein said terminalfunctionality has the general formula

where Z′ is a single bond or an alkylene group; R⁵ is an aryl groupcomprising two or more OR substituent groups; R⁶ is H, a substituted orunsubstituted aryl group which optionally can include one or morehydrolyzable protecting groups, R′, or JR′ where J is O, S, or —NR′ inwhich each R′ independently is a substituted or unsubstituted alkylgroup; and Q″ is the residue of a functionality that is reactive with atleast one type of reactive polymer but which itself is non-reactivetoward such polymers.
 4. The rubber composition of claim 1 wherein saidpolymer comprises terminal functionality that comprises an aryl groupcomprising at least two OH substituents.
 5. The rubber composition ofclaim 1 wherein Y comprises an —OH, —SH, —NHR², —CN, —C(O)R² or —NCOgroup where R² is H or a substituted or unsubstituted hydrocarbyl group.6. The rubber composition of claim 5 wherein Y is a primary amino group.7. The rubber composition of claim 1 wherein L is defined by —SiR¹¹_(m)(OR¹¹)_(3-m) where m is 1 or 2 and R¹¹ is a substituted orunsubstituted hydrocarbyl group, or

where n is an integer of from 2 to 5 inclusive, R² is H or a substitutedor unsubstituted hydrocarbyl group, and is a substituted orunsubstituted hydrocarbyl group.
 8. A vulcanizate prepared from therubber composition of claim
 1. 9. A method of making a rubbercomposition, said method comprising blending a polymer comprisingethylenic unsaturation and pendent or terminal functionality thatcomprises an aryl group comprising at least two OR substituents, whereinR is H or a hydrolyzable group, with either (1) filler particles thatcomprise oxides of silicon and bound residues of one or more compoundshaving the general formula YR¹L, or (2) one or more compounds defined bythe general formula YR¹L and filler particles that comprise oxides ofsilicon, where Y is a group reactive with said polymer functionality oran oxidation product thereof, R¹ is a hydrocarbylene group, and L is agroup that contains at least one Si—O bond, said method optionallyfurther comprising allowing said polymer to covalently bond to saidfiller particles.
 10. The method of claim 9 wherein said polymercomprises terminal functionality that comprises an aryl group comprisingat least two OR substituents.
 11. The method of claim 10 wherein saidterminal functionality has the general formula

where Z′ is a single bond or an alkylene group; R⁵ is an aryl groupcomprising two or more OR substituent groups; R⁶ is H, a substituted orunsubstituted aryl group which optionally can include one or morehydrolyzable protecting groups, R′, or JR′ where J is O, S, or —NR′ inwhich each R′ independently is a substituted or unsubstituted alkylgroup; and Q″ is the residue of a functionality that is reactive with atleast one type of reactive polymers but which itself is non-reactivetoward such polymers.
 12. The method of claim 10 wherein said terminalfunctionality comprises a phenyl group that comprises at least two ORsubstituents.
 13. The method of claim 9 wherein said compositioncomprises one or more compounds defined by the general formula YR¹L andat least one type of silica.
 14. The method of claim 9 wherein Ycomprises an —OH, —SH, —NHR², —CN, —C(O)R² or —NCO group with R² being Hor a substituted or unsubstituted hydrocarbyl group.
 15. The method ofclaim 9 wherein said composition comprises silica particles comprisingbound residues of one or more compounds having the general formula YR¹L.16. The method of claim 9 wherein said polymer comprises terminalfunctionality that comprises an aryl group comprising at least two OHsubstituents.
 17. The method of claim 9 wherein Y is a primary aminogroup.
 18. The method of claim 9 wherein L is defined by —SiR¹¹_(m)(OR¹¹)_(3-m) where m is 1 or 2 and R¹¹ is a substituted orunsubstituted hydrocarbyl group, or

where n is an integer of from 2 to 5 inclusive, R² is H or a substitutedor unsubstituted hydrocarbyl group, and R¹¹ is a substituted orunsubstituted hydrocarbyl group.
 19. The method of claim 9 furthercomprising blending at least one vulcanizing agent into said rubbercomposition.
 20. The method of claim 19 further comprising vulcanizingsaid rubber composition.